No, keep it classified as humid subtropical.

No, but classify it as something else (neither humid subtropical or temperate)

Yes, classify it as temperate.

I have been wondering about climate classifications. Based on average annual temperature and precip, a large chunk of the southeast/southcentral United States is lumped into the Humid Subtropical climate zone. But that seems misleading to people with agriculture or gardening interests, since subtropical officially implies that temperatures do not regularly fall below freezing. My experience with these southern zones (especially TN, AR, NC but as far south as panhandle of florida) is that it is USUALLY mild to hot, but it does get cold enough every year (i.e. below freezing) for long enough periods as to prevent subtropical plant species from becoming established in those zones. This is esp true in TN, OK, AR where normal temps actually fall below freezing during winter, but the hot as hell summer keeps the annual mean temp above the subtropical cutoff. This also applies to pipe regulations, "bridge may freeze signs", etc ...

So wouldn't it make more sense just to lump these regions into the temperate zone? Afterall, the vegetation is for the most part temperature deciduous in these areas.

I have seen several different definitions, which means there is probably no real consensus. But based on the criteria you mentioned, places like Paris, London, Seattle would all have subtropical climates. I've also heard that the location has to lie between 20 and 40 N/S and/or that it has to have an annual temp above 60F.

Not that this is of any real importance, but it seems to me that the purpose of calling a climate region "subtropical" is for agricultural reasons and agriculture assumes that subtropics generally remain above freezing, which currently classified subtropical climates do not. On the other hand, most mediterranean climates fit this requirement, though their annual averages are usually below 60F